Modular, ceramic, electron-discharge tube



Aug. 23, 1960 E. J. ALBERT MODULAR, CERAMIC, ELECTRON-DISCHARGE TUBE Filed April 16, 1956 J. Albert INVENTOR.

Edmond Edmond .1. Albert, Nashua, N.H., assignor, by mesne assignments, to Sanders Associates, Inc, Nashua, Na. a corporation of Delaware Filed Apr. 16, 1956, Ser. No. 578,211

Claims. (Cl. 313-250) This invention relates to modular devices for electronics. More particularly, the invention relates to modular, space-discharge tubes.

In the construction of modular packaging for electronic components as described in National Bureau of Standards Technical News Bulletin Number 11, volume 37, November 1953, it has been a problem to provide compatible space-discharge tubes. As described and illustrated in NBS Bulletin Number 11, such modules are typically formed of a plurality of congruently stacked, spaced, ceramic wafers having perimetrically disposed indentations formed therein. The wafers have metallic conductive paths afiixed thereto and are supported in place by riser wires or conductors disposed in the wafer indentations. The indentations are coated with silver which is caused to adhere to the riser wires as, for example, by soldering or brazing.

In the prior art'space-discharge tubes, particularly electron-discharge tubes, are formed primarily from glass envelopes and metal or phenolic bases. The electrodes typically are vertically supported by metallic conductors which extend from the base of the tube. Such tubes do not operate satisfactorily at temperatures in excess of 185 C. Furthermore, these tubes are extremely susceptible to mechanical shock and vibration. Additionally, these tubes are not readily integrated into modular units.

In the structure of modular, ceramic, space-discharge tubes as described and illustrated in a copending application entitled Modular Electron-Discharge Tube, filed April 16, 1956, Serial No. 578,385, now abandoned, by Christopher Karabats and James D. LeVan, it has been a problem to reduce the inter-electrode capacity. This problem arises because of the high dielectric constant of ceramic materials coupled with the presence of metallic conductive paths on opposite sides of a given ceramic wafer which connect different electrodes. The particular inter-electrode capacities producing considerable difiiculty are the control-grid-to-cathode and control-grid-to-plate capacities.

It is, therefore, an object of the invention to provide an improved modular, space-discharge tube operable at temperatures in excess of 600 C.

A further object of the invention is to provide an improved modular, space-discharge tube capable of withstanding a high degree of mechanical shock and vibration.

A still further object of the invention is to provide an tent improved modular, electron-discharge tube having re- 7 duced inter-electrode capacity.

In accordance with the invention there is provided a modular, space-discharge tube. The tube comprises a pair of end wafers and a plurality of inner wafers stacked between end wafers. The inner wafers have holes centrally formed therein. A plurality of staggered conductive paths are afiixed to opposite sides of the inner wafers. One of the paths extends into the central hole in one of the wafers. An electrode is secured longitudinally to the inside surface of the central hole in one of the wafers to confine contact of the extended path and the inside surface to present a minimum of conductive surface area to an adjacent electrode and thereby, minimize inter-electrode capacity.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawings:

Fig. 1 is a perspective view of an electron-discharge tube embodying the invention;

Fig. 2 is a perspective view, in exploded form and partially in section, of an electron-discharge tube embodying the invention; and

Fig. 3 is a sectional view of the embodiment in Fig. 1.

Description of the discharge tube in Figs. 1-3

Referring now to the drawings, there is here illustrated a modular, space-discharge tube. While the embodiment illustrated and described herein is particularly directed to an electron-discharge tube, the term space-discharge tube is employed to include both vacuum and gas discharge tubes in which either negative or positively charged particles are transmitted through space. The electrondischarge tube here illustrated is a twin-triode having a heater 13, a pair of cathodes 14, a pair of control grids 17, and a pair of anodes 16 contained within and supported by a plurality of congruently stacked, ceramic wafers. Thus, in detail, and referring particularly to Fig. 2, the tube comprises a plurality of congruently stacked, ceramic wafers 1:;a1ih, each having a metaiiic conductive path 11 afi'ixed thereto. The inner wafers 10b10g, inclusive, have circular holes 12 centrally formed therein. The end wafers lbs and llih enclose the ends of the tube and seal the discharge space formed by the holes 12. The heater element 13, disposed at approximately midpoint axially and diametrically of the holes 12, is secured between the middle pair of adjacent Wafers 19d and 10s. The cathodes 14, in the form of a pair of disks, are individually secured between different ones of the pairs of wafers 10c, 10d and 10c, 10

The control grid electrodes 17 have an annular ferrule member affixed to a grid disk 17b. The ferrule members are secured in the central holes respectively of the wafers lite and 19]", with each of the grid disks 17b facing its adjacent cathode 14. The diameter of the ferrule members 17a is so chosen as to require a press fit between the ferrule members and the inside surface of the central holes 12. Conductors 11a aflixed to wafers 10c and 10 each extend from a peripheral indentation 15 into the holes 12 as shown. The ferrules 17a contact the conductors 11a to effect an electrical connection therebetween. The ferrules 17a are secured to the inside surface of the holes 12 by means of Well-known ceramic-tometal seals.

The anodes 16 are disposed between end Wafers and the adjacent inner Wafers, one between the Wafers 10a and 16b and the other between the wafers 10g and 19h. The electrodes other than the grids 17 are flanged to enable peripheral securing between pairs of wafers in contact with a conductive path 11 on each of these wafers to provide means for making external connections to the electrodes and are shaped, as shown, to provide a suitable spacing between electrodes.

The wafers have perimetrically disposed indentations 15 to provide means for external connections. The conductive paths 11 are terminated in and connected to selected indentations 15 for effecting a desired matrix of connections. The indentations 15 are preferably silvercoated and solder-filled and a plurality of riser wires 18 are disposed therein and, for example, soldered or welded in place. The tube is assembled by effecting ceramic-to- '6 cubic inchesfor standard receiving tubes.

metal seals between the wafers and the electrodes and. ceramic-to-ceramic seals between the wafers.

Such ceramic-to-metal seals are well known; for example, see Materials Technologyfot Electron Tubesi'by Walter,- H. Kohl; published; by: Reinhold Publishing Corporation, 1951, chapter 16, pages 403-421. The tube being of modularform may also be mounted as an extended portion of-a module with common riser connections-being made-tothe module and the modular tube.

In prior art mod'ularpce'ramic tubes, it. has been found that inter-electrode capacitancegior example, the control-grid-to-cathode and control-grid-tp=anode .1. capacitances arein the order of l2'micromicrofar'ads. .;.The effect of such a high inter-electrode capacitancezisto severely limit the performance ofthe tube 'atihigh frequencies. It will be apparent that the structure of the control grids 17 may be reproduced for the other electrodes to obtain the minimum overall inter-electrode capacity; Merelybyutilizing the structure of the control grids 17 as disclosed herein produces a decrease in grid-to-cathode-and grid-to-anode capacitance from 12 micromicrofarads to'less than 2 micromicrofarads';

One form of the ceramic tube embodying the present invention is .875" square and .28" inheight. The volume of a 'twin-triode' tube embodying the present invention can be less than .12 cubic inch as compared with Such a tube, however; is capable'of operating at temperatures in excess of 600 C. as compared with the conventional limitation to 185 C. Furthermore, tubes embodying the present invention are capable of dissipating in excess of 8 wattsof power as comparedwith conventional tubes which are limited'to 1 watt.

While applicant does not intend to be limited to any particular shapes, sizes or materials of parts in the embodiment of the invention just described; there follows a set of dimensions and materials for the more important parts which have been found to be particularly suitable for a twin-triode amplifier tube of the type represented in Figs. 1 and'2:

Heater 13.75 long by .026 in diameter, formed from ,002 tungsten 'wire with .002 aluminum oxide insulation; Cathodes 14outer diameter of flange .350"; outer diameter of disk .280"; materialnickel base with a coating of .002" barium strontium;

Wafer holes 12-3-40" in'diameter;

7 changes and modifications as fall within the true spirit present a minimum of conductive surface area to an adjacent electrode and, thereby, minimize inter-electrode capacity.

2. A modular, space-discharge tube, comprising: a pair of end wafers; a plurality of inner wafers stacked with said end wafers and having holes centrally formed Control grids 17-ferrule fizz-outer diameter .345"; I

diameter of grid: disk 17b .240"; height .035.,' ;,rnaterial.grid mesh .001" thick nickel; ferrule .002" thick nickel; V

Anodes 16 fiange outer diameter. .410"; flange inner diameter .330; outerdiameter of anode; disk .280";

height .055"; material+nickel .005". thick; Spacing between end wafers and anodes: 16-.053";

-Anodes 16 to control grids 17 spacing...018";.

Control grid 17 to cathode 14 spacing-.005"; and Total thickness of the two cathodes 14 and heater 13 structure-e040.

that the discharge tube ofthe invention fulfills a critical 7 need in an area where other modern devices such as transistors, amplifiers, capacitiveaniplifiers' and conventional discharge-tubesare unsuitable.

While there has'been described what is at present considered to beVthe preferred embodiment of'this invention, itfWill be obvious to those skilled in the art that various changes and modifications may be made thereinlwith'out' departing from the invention, and it is, thereforefanned in' the appended claims" to cover all" such elementsecured between a pair of-adjacent wafers and therein; a plura lity ofstaggered conductive paths aflixed to opposite sides of said inner wafers, one of said paths extending into the central holesin one each o f two said wafers; and a control grid electrode having an annular ferrule member secured longitudinally to the inside surface of said central hole in one ofsaid wafers to confine contact to said extended path and said inside surface to present a minimum'conductive surface area to an adjacent electrode and, thereby, minimize inter-electrode capacity. 7 a p 3. A modular, ceramic, electron-discharge tube, comprising: a pair of end ceramic, wafers having perimetrically disposed indentations formed therein; a plurality of inner, ceramic wafers with perimetrically disposed indentations andistacked'congruently with said end wafers, said inner wafers having holes centrally therein; a plurality of staggered conductive paths affixed to opposite sides of said inner wafers, a pair of said paths each extending into the central hole in one each of two said wafers; a' heater element secured between a, pair of adjacent inner'wafers and disposed in said holes; a pair of cathode disks disposed adjacent opposite sides of said heater and secured to adjacent inner wafers;,a pair of control grid electrodes" each having anannular ferrule member secured to .the insidei'surface. of said central hole in one: each of saidwafers and contacting the path extending therein; a pair. of anodes each disposed between an end wafer and its adjacent inner wafer with said control grids between said modes and cathodes; metallic conductive paths aflixed to saidwafers and selectively connecting said electrodes and heater to said indentations; and a'plurality' of" riser conductors disposed in said indentations and connected'to' said paths providing an integrah'multimnit, modular electrorr'discharge 'tube with external connections;

4. A modular, space-dischargetube, 'comprisingi apair 'of' end wafers; an inner wafer stacked between said end wafers and having a central hole, said holeprovid- 'ing. a discharge spaceia conductive path affixedtozaside of said inner wafer and extending from a wafer extremity into the inside wafer surface defining said central hole; and

an electrode secured longitudinally to said insid'e wafer surface of said'hole to confine 'contact'to said extended path in said hole and said inside surface to present a minimum conductive surface area to an adiacent electrode and thereby minimize electrode capacity.

7 5. A modular, ceramic, electron-discharge tube, coinprisingi a pair of end ceramic wafers having pen'metrically disposed indentations; a plurality of inner; ceramic wafers with perirne trically disposed indentations corresponding with the'first said indentations and stacked, be-

tween said end wafers congruently therewith, said inner ,wafers having central holes providing a discharge space;

a conductive path afiixed to the flat side of one of said inner wafersiextendingfrom one-end of its indentations into the inside wafersurface of its central hole; a heater disposed in said space; a cathode disk secured between a pair of adjacent wafers and disposed in said space adjacent said heater; a control grid electrode having an annular member secured longitudinally to said inside surface to confine contact to an extended path and said inside surface to present a minimum conductive surface area to an adjacent electrode and, thereby, minimize inter-electrode capacity; an anode secured between an end wafer and its adjacent inner wafer and disposed in said space with said control grid between said anode and said cathode; conductive paths afiixed to said wafers and selectively connecting said electrode and heater to said indentations; and a plurality of riser conductors disposed in said indentations and connected to said paths providing an integral, multi-unit, modular, ceramic electrondischarge tube with external connections.

References Cited in the file of this patent UNITED STATES PATENTS 2,441,792 Brian May 18, 1948 2,731,578 McCullough Jan. 17, 1956 10 2,740,067 Sorg Mar. 27, 1956 FOREIGN PATENTS 458,702 Great Britain Dec. 24, 1936 

